Abstract:

An ultrasound diagnosis apparatus: in conjunction with change of a
projection region using an operation part, changes a viewpoint to a
position where a reference cross section is in front and the changed
projection region is on the back; in conjunction with change of the
viewpoint using the operation part, changes a region where the reference
cross section is in front and the changed viewpoint is on the back to the
projection region; in conjunction with change of a scanning region using
the operation part, changes the viewpoint to a position where the
reference cross section is in front and the changed scanning region is on
the back; in conjunction with change of the viewpoint using the operation
part, changes the scanning region to a region where the reference cross
section is in front and the viewpoint is on the back; and then executes
rendering.

Claims:

1. An ultrasound diagnosis apparatus that acquires volume data by
transmitting and receiving ultrasonic waves to and from an inside of a
subject body and generates an image based on the volume data, the
ultrasound diagnosis apparatus comprising:a first image generator
configured to generate a cross sectional image of a designated or
predefined reference cross section based on the volume data;a second
image generator configured to generate a projection image by rendering a
predetermined projection region in a direction from a predetermined
viewpoint, based on the volume data;a display configured to display the
cross sectional image generated by the first image generator and the
projection image generated by the second image generator; andan operation
part with which change of the projection region is inputted,wherein the
second image generator, in conjunction with the change of the projection
region by the operation part, changes the viewpoint to a position where
the reference cross section is in front and the changed projection region
is on the back, and thereafter renders the changed projection region.

2. The ultrasound diagnosis apparatus according to claim 1, wherein the
second image generator changes the viewpoint around an axis of a depth
direction in a local coordinate system of the volume data.

3. The ultrasound diagnosis apparatus according to claim 1, wherein the
second image generator changes the viewpoint when the projection region
is changed beyond the reference cross section in the change by the
operation part.

4. The ultrasound diagnosis apparatus according to claim 1, wherein the
second image generator previously stores information representing the
projection region and range information of the viewpoint where the
reference cross section is in front and the projection region is on the
back, so as to be linked to each other.

5. An ultrasound diagnosis apparatus that acquires volume data by
transmitting and receiving ultrasonic waves to and from an inside of a
subject body and generates an image based on the volume data, the
ultrasound diagnosis apparatus comprising:a first image generator
configured to generate a cross sectional image of a designated or
predefined reference cross section, based on the volume data;a second
image generator configured to generate a projection image by rendering a
predetermined projection region in a direction from a predetermined
viewpoint, based on the volume data;a display configured to display the
cross sectional image generated by the first image generator and the
projection image generated by the second image generator; andan operation
part with which change of the viewpoint is inputted,wherein the second
image generator, in conjunction with the change of the viewpoint by the
operation part, changes the projection region where the reference cross
section is in front and the changed viewpoint is on the back, and
thereafter executes a rendering operation of projecting the projection
region to a region in a direction from the changed viewpoint.

6. The ultrasound diagnosis apparatus according to claim 5, wherein with
the operation part, the change of the viewpoint around an axis of a depth
direction in a local coordinate system of the volume data is inputted.

7. The ultrasound diagnosis apparatus according to claim 5, wherein the
second image generator changes the projection region when the viewpoint
is changed beyond the reference cross section in the change by the
operation part.

8. The ultrasound diagnosis apparatus according to claim 5, wherein the
second image generator previously stores information representing the
projection region and range information of the viewpoint where the
reference cross section is in front and the projection region is on the
back, so as to be linked to each other.

9. An ultrasound diagnosis apparatus that acquires volume data of a
scanning region by transmitting and receiving ultrasonic waves to and
from an inside of a subject body and generates an image of the scanning
region based on the volume data, the ultrasound diagnosis apparatus
comprising:a first image generator configured to generate a cross
sectional image of a designated or predefined reference cross section,
based on the volume data;a second image generator configured to generate
a projection image by rendering the scanning region in a direction from a
predetermined viewpoint, based on the volume data;a display configured to
display the cross sectional image generated by the first image generator
and the projection image generated by the second image generator; andan
operation part with which change of the scanning region is
inputted,wherein the second image generator, in conjunction with the
change of the scanning region by the operation part, changes the
viewpoint to a position where the reference cross section is in front and
the changed scanning region is on the back, and thereafter renders the
changed scanning region.

10. The ultrasound diagnosis apparatus according to claim 9, wherein the
second image generator changes the viewpoint around an axis of a depth
direction in a local coordinate system of the volume data.

11. The ultrasound diagnosis apparatus according to claim 9, wherein the
second image generator changes the viewpoint when the projection region
is changed beyond the reference cross section in the change by the
operation part.

12. The ultrasound diagnosis apparatus according to claim 9, wherein the
second image generator previously stores information representing the
scanning region, range information of the viewpoint where the reference
cross section is in front and the scanning region is on the back, and
information representing a region to be projected, so as to be linked to
each other.

13. An ultrasound diagnosis apparatus that acquires volume data of a
scanning region by transmitting and receiving ultrasonic waves to and
from an inside of a subject body and generates an image of the scanning
region based on the volume data, the ultrasound diagnosis apparatus
comprising:a transmission controller configured to control the
transmission and reception of the ultrasonic waves to and from the
scanning region;a first image generator configured to generate a cross
sectional image of a designated or predefined reference cross section,
based on the volume data;a second image generator configured to generate
a projection image by rendering the scanning region in a direction from a
predetermined viewpoint, based on the volume data;a display configured to
display the cross sectional image generated by the first image generator
and the projection image generated by the second image generator; andan
operation part with which change of the viewpoint is inputted,
wherein:the transmission controller, in conjunction with the change of
the viewpoint by the operation part, changes the scanning region to a
region where the reference cross section is in front and the changed
viewpoint is on the back; andthe second image generator executes a
rendering process of projecting the scanning region in a direction from
the changed viewpoint, in conjunction with the change of the viewpoint by
the operation part.

14. The ultrasound diagnosis apparatus according to claim 13, wherein with
the operation part, the change of the viewpoint around an axis of a depth
direction in a local coordinate system of the volume data is inputted.

15. The ultrasound diagnosis apparatus according to claim 13, wherein:the
second image generator changes the projection region when the viewpoint
is changed beyond the reference cross section in the change by the
operation part.

16. The ultrasound diagnosis apparatus according to claim 13, wherein:the
second image generator previously stores information representing the
scanning region, range information of the viewpoint where the reference
cross section is in front and the scanning region is on the back, and
information representing a region to be projected, so as to be linked to
each other.

Description:

BACKGROUND OF THE INVENTION

[0001]1. Field of the Invention

[0002]The present invention relates to an ultrasound diagnosis apparatus
that generates a projection image by rendering volume data acquired by
transmission and reception of ultrasonic waves and displays the
projection image.

[0003]2. Description of the Related Art

[0004]With the rapid enhancement of computation by computers in recent
years, it has become possible to generate a three-dimensional moving
image by rendering 4D data acquired by continuously scanning the inside
of a subject, and to make a diagnosis and provide treatment based on the
three-dimensional moving image. For example, as shown in Japanese
Unexamined Patent Application Publication No. 2004-275223, an ultrasound
diagnosis apparatus can also acquire 4D data with a two-dimensional array
ultrasound probe capable of three-dimensionally transmitting and
receiving an ultrasonic beam to and from a space inside a subject and
generate a three-dimensional moving image by rendering the 4D data.

[0005]Rendering is creation of a projection moving image representing a
three-dimensional figure by projecting a region to be rendered in a
viewing direction. A rendering method is, for example, the surface
display method and the volume rendering method. In the volume rendering
method, voxel data of a region viewed from a viewpoint is sampled,
transmission of light in accordance with opacity and reflection to the
viewpoint are calculated, and a projection moving image is generated
while shading is applied.

[0006]In this rendering, it is necessary to properly specify a viewpoint
and a region to be rendered. Moreover, an ultrasound diagnosis apparatus
configured so that a scanning region to and from which ultrasonic waves
are transmitted and received is variable also needs to properly specify
the scanning region. With the rapid enhancement of computation by
computers in recent years, it has become easier to change the aspects of
rendering, e.g., change a viewpoint, change a region to be rendered, and
change a region to be scanned. When an operator inputs change of the
viewpoint and the region, the ultrasound diagnosis apparatus immediately
executes re-rendering and displays an image.

[0007]However, since the operation of changing the aspects of rendering
has become possible, such a problem has arisen that it is impossible to
display a projection moving image taken from a desired reference cross
section unless the operator properly designates the viewpoint and the
region to be rendered, or properly designates a region to be scanned, the
viewpoint and a region to be rendered. For example, it is assumed that
one region across a reference cross section is scanned and the one region
is rendered in a state that a viewpoint is set so that the reference
cross section is in front and the one region is on the back. If the
operator changes the position of the viewpoint from the above state to
the reverse side beyond the reference cross section, the rendering is
executed in an aspect that a plane opposite to the reference cross
section is the surface, with the result that it is difficult to observe
the reference cross section from the projection image.

[0008]In other words, when performing a viewpoint changing operation, in
response to the operation, the operator must perform a changing operation
to scan the other region across the reference cross section, and further
perform a changing operation to render the other region. If not, a
projection image with a reference cross section viewed from the changed
viewpoint as the surface cannot be generated.

SUMMARY OF THE INVENTION

[0009]An object of the present invention is to provide an ultrasound
diagnosis apparatus that, even if some of the conditions of rendering are
changed, can maintain an aspect of rendering from a viewpoint with a
reference cross section set in front of a projection region, without
performing a number of complicated changing operation steps in response
to the change of the conditions.

[0010]In a first aspect of the present invention: a cross sectional image
of a designated or predefined reference cross section is generated based
on volume data acquired by transmitting and receiving ultrasonic waves to
and from the inside of a subject; a projection image is generated by
rendering a predetermined projection region in a predetermined viewing
direction; and the cross sectional image and the projection image are
displayed on a display.

[0011]When change of the projection region is inputted through an
operation part, in conjunction with the change, the viewpoint is changed
to a position in which the reference cross section is in front and the
changed projection region is on the back, and then this changed
projection region is rendered.

[0012]Further, in a second aspect of the present invention: a cross
sectional image of a designated or predefined reference cross section is
generated based on volume data acquired by transmitting and receiving
ultrasonic waves to and from the inside of a subject; a projection image
is generated by rendering a predetermined projection region in a
predetermined viewing direction; and the cross sectional image and the
projection image are displayed on a display. When change of the viewpoint
is inputted through an operation part, in conjunction with the change, a
region in which the reference cross section is in front and the changed
viewpoint is on the back is changed to the projection region, and then
executing a rendering process of projecting in a direction from the
changed viewpoint is performed.

[0013]According to the first and second aspects of the present invention,
it is possible to maintain an aspect of rendering from the viewpoint with
the reference cross section set in front of the projection region without
executing a number of complicated changing operation steps such as an
operation of adjusting the projection region after an operation of
adjusting the viewpoint and vice versa. Therefore, grasp of a
three-dimensional structure is facilitated, and the efficiency of
observation of the inside of a subject is increased.

[0014]Further, in a third aspect of the present invention: a cross
sectional image of a designated or predefined reference cross section is
generated based on volume data of a scanning region acquired by
transmitting and receiving ultrasonic waves to and from the inside of a
subject; a projection image is generated by rendering the scanning region
in a predetermined viewing direction; and the cross sectional image and
the projection image are displayed on a display. When change of the
scanning region is inputted through an operation part, in conjunction
with the change of the scanning region, the viewpoint is changed to a
position in which the reference cross section is in front and the changed
scanning region is on the back, and then the changed scanning region is
rendered.

[0015]Further, in a fourth aspect of the present invention: a cross
sectional image of a designated or predefined reference cross section is
generated based on volume data of a scanning region acquired by
transmitting and receiving ultrasonic waves to and from the inside of a
subject; a projection image is generated by rendering the scanning region
in a predetermined viewing direction; and the cross sectional image and
the projection image are displayed on a display. When change of the
viewpoint is inputted through an operation part, in conjunction with the
change of the viewpoint, the scanning region is changed to a region in
which the reference cross section is in front and the changed viewpoint
is on the back, and then a rendering process of projecting this scanning
region in a direction from the changed viewpoint is executed.

[0016]According to the third and fourth aspects of the present invention,
it is possible to maintain an aspect of rendering from the viewpoint with
the reference cross section set in front of the projection region without
executing a number of complicated changing operation steps, e.g.,
performing an operation of adjusting the position of the viewpoint and an
operation of changing the projection region after an operation of
changing the scanning region, or executing an operation of changing the
scanning region and the projection region after changing the viewpoint.
Therefore, grasp of a three-dimensional structure is facilitated, and the
efficiency of observation of the inside of a subject is increased.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 illustrates the configuration of an ultrasound diagnosis
apparatus according to this embodiment.

[0022]FIG. 6 illustrates an aspect of re-generating an image in response
to an operation of changing a viewpoint or an operation of switching a
projection region.

[0023]FIG. 7 illustrates a flow chart showing an operation of changing a
viewpoint and a projection region in conjunction and re-rendering by the
ultrasound diagnosis apparatus.

[0024]FIG. 8 illustrates a flow chart showing an operation of changing a
scanning region and re-rendering.

[0025]FIG. 9 illustrates an example of sectioning of a scanning region or
a projection region viewed from a secondary scanning direction.

DETAILED DESCRIPTION OF THE EMBODIMENT

[0026]A preferred embodiment of an ultrasound diagnosis apparatus
according to the present invention will be specifically described below
with reference to the drawings.

[0027]FIG. 1 is a block diagram illustrating the configuration of an
ultrasound diagnosis apparatus according to this embodiment. FIG. 2 is a
schematic view illustrating piezoelectric elements of an ultrasound
probe. As shown in FIG. 1, an ultrasound diagnosis apparatus 1 of this
embodiment is connected to an ultrasound probe 2 capable of
three-dimensional scan. This ultrasound diagnosis apparatus 1 causes the
ultrasound probe 2 to transmit and receive ultrasonic waves to and from
inside the body of a subject, generates an image of the inside of the
subject based on the received ultrasonic waves, and causes a monitor 7 to
display this image so as to be visually recognizable. In particular, this
ultrasound diagnosis apparatus 1 three-dimensionally transmits and
receives ultrasonic waves to and from the inside of the subject,
generates volume data continuously in a chronological order, and displays
a three-dimensional moving image.

[0028]As shown in FIG. 2, the ultrasound probe 2 has a configuration in
which a plurality of piezoelectric elements 2a are two-dimensionally
arranged.

[0029]The piezoelectric elements 2a are composed of a ceramic material,
such as lead zirconate titanate (Pb(Zr,Ti)O3), lithium niobate (LiNbO3),
barium titanate (BaTiO3), and lead titanate (PbTiO3). The piezoelectric
element 2a is an acoustic/electric reversible conversion element, and
oscillates ultrasonic waves when pulse signals are applied thereto, and
outputs echo signals in accordance with the intensity of the ultrasonic
waves when receiving the ultrasonic waves. An image of the inside of the
subject is visualized by processing the echo signals in the ultrasound
diagnosis apparatus 1. The ultrasound probe 2 in which the plurality of
piezoelectric elements 2a are two-dimensionally arranged transmits and
receives ultrasonic waves three-dimensionally, and receives volume data
radiating from the surface of the ultrasound probe 2, as the echo
signals.

[0030]The ultrasound diagnosis apparatus 1 has a transmitter 3, a receiver
4, a signal processor 5, an image generator 6, a monitor 7, a controller
8, and a console 12. The transmitter 3 and the receiver 4 are connected
to the ultrasound probe 2. The image generator 6 has a coordinate
transforming part 61, a sectional image generator 62, and a projection
image generator 63.

[0031]The transmitter 3 is a transmission controller that generates pulse
signals and applies the pulse signals to the piezoelectric elements 2a,
thereby controlling a region scanned with ultrasonic waves. The
transmitter 3 has a pulse generator 11, a delay circuit 10, and a
high-output circuit 9.

[0032]The pulse generator 11 is a circuit that generates pulse signals.
The pulse generator 11 internally has a clock generator that generates
primitive signals and, based on the frequency of the primitive signals,
outputs pulse signals with a frequency represented by preset frequency
data. The delay circuit 10 is a circuit that delays the pulse signals
generated by the pulse generator 11 for each of the piezoelectric
elements 2a. The delay circuit 10 generates a delay based on preset delay
data. For example, when a longer delay is applied to the piezoelectric
elements 2a arranged on one side, ultrasonic beams are focused on the
other side. In other words, the ultrasonic beams are oscillated within a
scanning range in the main scanning direction in the delay sequence by
the pulse generator 11. The high-output circuit 9 converts the delayed
pulse signals into high voltage, and applies it to the piezoelectric
elements 2a. The scanning range in the secondary scanning direction
changes the line of the piezoelectric elements 2a to which the high
voltage is applied.

[0033]The receiver 4 receives an echo signal at each focal point within a
scanning region from the ultrasound probe 2. This receiver 4 amplifies
the echo signals and converts them into digital signals. Moreover, the
receiver 4 applies a delay time necessary for determining reception
directionality to the echo signals outputted from the respective
piezoelectric elements 2a, performs phasing addition, and generates a
single echo signal in which reflection components from a direction
according to the reception directionality are enhanced. The receiver 4
outputs the processed echo signal to the signal processor 5.

[0034]The signal processor 5 visualizes amplitude information of the echo
signals at the respective focal points within the scanning region, and
generates B-mode volume data from all of them. The volume data is a
collection of echo signals at the respective focal points within the
scanning region. More specifically, a band-pass filter process is
executed on the echo signals outputted from the receiver 4, and then the
envelope curve of the output signals is detected. The detected data is
compressed by logarithmic transformation.

[0035]The image generator 6 executes an MPR process on the volume data to
generate a sectional image, and renders the volume data to generate a
projection image.

[0036]FIG. 3 is a view illustrating an aspect of generating an image by
the generator 6. The coordinate transforming part 61 is a digital scan
converter, which executes, on the volume data, modeling transformation to
the world coordinate system (Xw, Yw, Zw) and the viewing coordinate
system (Xv, Yv, Zv) that are represented by orthogonal coordinates. The
world coordinate system is a coordinate system that defines the entire
three-dimensional space.

[0037]The viewing coordinate system is a coordinate system for rendering
in which a viewpoint Vp is the original point and a direction looking
from the viewpoint Vp is the Z axis. The positional relationship of the
viewing coordinate system with the world coordinate system is previously
defined.

[0038]When the viewpoint Vp is changed by using the console 12, or the
viewpoint Vp is changed in conjunction, the coordinate transforming part
61 re-defines the relationship between the changed viewpoint coordinate
system and the world coordinate system by modeling transformation.

[0039]The volume data is acquired in a local coordinate system. The local
coordinate system is three dimensions represented by a distance and two
angles. The distance is a distance between the position of the ultrasound
probe 2 and the focal point. One of the angles is an angle in the main
scanning direction formed between the axis Ax extending in the depth
direction from the center of gravity of the two-dimensional arrangement
of the piezoelectric elements 2a and the line extending from the center
of gravity to the focal point. The other angle is an angle in the
secondary scanning direction formed between the abovementioned lines. The
coordinate transforming part 61 executes, on the volume data acquired in
the local coordinate system, modeling transformation to the world
coordinate system (Xw, Yw, Zw). Furthermore, the coordinate transforming
part 61 executes, on the volume data of the world coordinate system,
modeling transformation to the viewing coordinate system.

[0040]The sectional image generator 62 is a first image generator that
executes section conversion on a reference cross section S of the volume
data by the MPR process and generates a sectional moving image
(hereinafter referred to as an S-sectional moving image Ds) in the world
coordinate system. The reference cross section S is predefined. For
example, the reference cross section S may be a plane in the main
scanning direction including the axis Ax extending in the depth direction
from the center of gravity of the two-dimensional arrangement of the
piezoelectric elements 2a.

[0041]The sectional image generator 62 sequentially generates frame data
of the S-sectional moving image Ds in which the voxel values of voxels
arranged on the plane are two-dimensionally arranged, for each of the
volume data sequentially generated.

[0042]The projection image generator 63 is a second image generator that
performs projection transformation by rendering with a previously
sectioned region A or B of a space represented by volume data as a
projection region and generates a projection image (hereinafter referred
to as an S-side projection moving image Dp) in the viewing coordinate
system. The space is sectioned into the regions by the reference cross
section S. The rendering by the projection image generator 63 may be
volume rendering, for example. The volume rendering is so-called
transmission projection transformation, which is a method of calculating
the transmission of light in accordance with opacity and reflection to
the viewpoint Vp and sequentially generating frame data of the S-side
projection moving image Dp while shading. In other words, a side closer
to the viewpoint Vp is reflected more on the S-side projection moving
image Dp.

[0043]The viewpoint Vp and the projection region in rendering are
determined in accordance with the positional relationship between the
reference cross section S and the region A or B to be rendered. More
specifically, the projection image generator 63 sets the region A or B
positioned on the back of the reference cross section S when viewed from
the viewpoint Vp, as the projection region. Alternatively, the projection
image generator 63 places the viewpoint Vp on the back of the reference
cross section S when viewed from the projection region. In other words,
rendering is performed so that the reference cross section S side is
reflected more on the S-side projection moving image Dp. For example,
when one side is the region A and the other side is the region B across
the reference cross section S and the viewpoint Vp is set on the region A
side, the region B that is on the back of the reference cross section S
when viewed from the viewpoint Vp becomes the projection region. The
projection image generator 63 determines the viewpoint Vp or the
projection region in accordance with the positional relationship in the
world coordinate system between the viewpoint Vp and the reference cross
section S.

[0044]That is to say, assuming volume data is placed at a position that
does not include the original point of the world coordinate system, if
the viewpoint Vp is on the side of the original point of the world
coordinate system from the reference cross section S, a region on the
back of the reference cross section S in the world coordinate system will
be regarded as the projection region. If the reference cross section S is
on the side of the original point of the world coordinate system from the
viewpoint Vp, a region on the original point side from the reference
cross section S in the world coordinate system will be regarded as the
projection region. If the region on the original point side from the
reference cross section S in the world coordinate system is the
projection region, the viewpoint Vp is placed on the back of the
reference cross section S in the world coordinate system. If a region on
the back of the reference cross section S in the world coordinate system
is the projection region, the viewpoint Vp is placed on the original
point side from the reference cross section S in the world coordinate
system. In change of the viewpoint Vp, it is moved axisymmetrically about
the axis Ax extending in the depth direction from the center of gravity
of the two-dimensional arrangement of the piezoelectric elements 2a.

[0045]The sectional image generator 62 executes section transformation by
the MPR process on a cross section intersecting the projection region
among planes that are orthogonal to the reference cross section S and
along the axis Ax extending in the depth direction from the center of
gravity of the two-dimensional arrangement of the piezoelectric elements
2a, and generates a sectional image (hereinafter referred to as a
T-sectional moving image Dt).

[0046]The controller 8 includes a CPU (central processing unit) and
controls the delay circuit 10, the image generator 6 and the monitor 7 in
response to an operation of the console 12. The console 12 is a keyboard
or a trackball and is an operation part through which it is possible to
input rotation of the viewpoint Vp or change of the projection region.
The monitor 7 is a display such as an LCD (liquid crystal display) and a
CRT (cathode ray tube), and displays a sectional image and a projection
image generated by the image generator 6.

[0047]FIG. 4 is a schematic view illustrating a display screen that
displays a tomographic image and a projection image. The S-sectional
moving image Ds, the T-sectional moving image Dt, and the S-side
projection moving image Dp generated by the image generator 6 are
displayed on the monitor 7. Further, a scannable range frame 71
representing a range that can be scanned by the ultrasound probe 2 is
displayed together with a cursor 72 on the screen. In the scannable range
frame 71, a probe object 73 of the ultrasound probe 2, an S-section frame
74 representing the S-sectional moving image Ds, a T-section frame 75
representing the T-sectional moving image Dt and a viewpoint object 76 of
the viewpoint Vp show the positional relationship of the ultrasound probe
2, the S-sectional moving image Ds, the T-sectional moving image Dt, the
S-side projection moving image Dp and the viewpoint Vp. A region
including the T-section frame 75 is a projection region to be projected
as the S-side projection moving image Dp.

[0048]FIG. 5 is a schematic view illustrating the console 12. The console
12 is an operation part to which a trackball 121 and a knob 122 are
attached.

[0049]When the trackball 121 is rotated, the controller 8 causes the
cursor 72 displayed on the monitor 7 to move. When the cursor 72 is put
on the viewpoint object 76 and the trackball 121 is rotated while being
pressed, the controller 8 changes the display position of the viewpoint
object 76. The controller 8 changes the display position of the viewpoint
object 76 so as to axially rotate or axially move around the axis Ax of
the modeling coordinate system extending in the depth direction from the
center of gravity of the two-dimensional arrangement of the piezoelectric
elements 2a. Moreover, the knob 122 is a switch for changing the
projection region. For example, the knob 122 can be switched between
positions for selecting the region A and the region B adjacent to each
other across the reference cross section S. When the knob 122 is switched
to the region A, the controller 8 controls to display the T-section frame
75 so as to cross the region A. When the knob 122 is switched to the
region B, the controller 8 controls to display the T-section frame 75 so
as to cross the region B. Moreover, the controller 8 outputs, to the
image generator 6, a signal representing the position coordinate of the
changed viewpoint Vp in the world coordinate system or a signal
representing the switched projection region.

[0050]FIG. 6 is a schematic view illustrating an aspect of re-generating
an image in response to the operation of changing the viewpoint Vp or the
operation of switching the projection region by the image generator 6.
When the position of the viewpoint Vp is changed, the projection image
generator 63 generates the S-side projection moving image Dp with the
region A or B as the projection region, which exists on the back of the
reference cross section S when viewed from the viewpoint Vp. In other
words, the projection image generator 63 samples a group of voxel data of
the region A or B existing on the back of the reference cross section S
when viewed from the changed viewpoint Vp, calculates the transmission of
light in accordance with opacity and reflection to the changed viewpoint
Vp, and sequentially generates frame data of the S-side projection moving
image Dp while shading.

[0051]More specifically, the projection image generator 63 compares the
position of the viewpoint Vp with the position of the reference cross
section S in the world coordinate system and, if the viewpoint Vp is
positioned on the original point side from the reference cross section S
in the world coordinate system, the S-side projection moving image Dp is
generated with the region B as the projection region, which exists on the
back of the reference cross section S. On the other hand, if the
viewpoint Vp is positioned on the back of the reference cross section S
in the world coordinate system, the S-side projection moving image Dp is
generated with the region A as the projection region, which exists on the
original point side from the reference cross section S. Here, modeling
transformation is executed on the volume data as the absolute location of
the world coordinate system defined beforehand.

[0052]Therefore, the projection image generator 63 may be configured to
previously store range information of the world coordinate system of the
viewpoint Vp and a coordinate range in the world coordinate system of the
region set as the projection region in combination and render by sampling
the group of voxel data in the coordinate range combined with the range
to which the viewpoint Vp after the change belongs.

[0053]Further, when the projection region is switched, the projection
image generator 63 moves the viewpoint Vp so that the projection region
exists on the back of the reference cross section S when viewed from the
viewpoint Vp, and generates the S-side projection moving image Dp. In
other words, the projection image generator 63 samples the group of voxel
data of the region A or B existing on the back of the reference cross
section S when viewed from the original point after the coordinate
transformation, i.e., from the changed viewpoint Vp, calculates the
transmission of light in accordance with opacity and reflection to the
changed viewpoint Vp, and sequentially generates frame data of the S-side
projection moving image Dp while shading.

[0054]More specifically, the projection image generator 63 compares the
position of the projection region with the position of the viewpoint Vp
in the world coordinate system. If the viewpoint Vp and the projection
region are on the same side with respect to the reference cross section S
as a result of the comparison, the coordinate transforming part 61
changes the position of the viewpoint Vp axisymmetrically about the axis
Ax extending in the depth direction from the center of gravity of the
two-dimensional arrangement of the piezoelectric elements 2a, and then
the projection image generator 63 renders the projection region from the
side of the changed viewpoint Vp.

[0055]Here, modeling transformation is executed on the volume data as the
absolute location of the world coordinate system determined beforehand.

[0056]Therefore, the projection image generator 63 may be configured to
render by previously associating the combination of the range information
of the world coordinate system of the viewpoint Vp and the coordinate
range in the world coordinate system of the region set as the projection
region with a switch of the knob 122, and sampling the group of voxel
data in the switched coordinate range.

[0057]Thus, when the viewpoint Vp is changed, the image generator 6
changes the projection region to be rendered in conjunction therewith and
thereafter executes re-rendering. Moreover, when the projection region is
changed, the image generator 6 changes the viewpoint Vp in conjunction
therewith and thereafter executes re-rendering. In other words, in order
to execute rendering in a state that the reference cross section S is
always in front of the viewpoint Vp, if the viewpoint Vp is changed
beyond the reference cross section S, the image generator 6 changes the
projection region in conjunction therewith and thereafter executes
rendering, whereas if the projection region is changed beyond the
reference cross section S, the image generator 6 changes the viewpoint Vp
in conjunction therewith and thereafter executes rendering.

[0058]FIG. 7 is a flow chart illustrating the operation of the ultrasound
diagnosis apparatus 1 for changing the viewpoint Vp and the projection
region in conjunction and executing re-rendering. When the display
position of the viewpoint object 76 is moved by operating the trackball
121 of the console 12 (S01, Yes), the projection image generator 63
sequentially generates frame data of the S-side projection moving image
Dp with the region A or B as the projection region, which exists on the
back of the reference cross section S when viewed from the viewpoint Vp
(S02).

[0059]Further, when the projection region is switched by operating the
knob 122 of the console 12 (S03, Yes), the coordinate transforming part
61 moves the viewpoint Vp axisymmetrically about the axis Ax so that the
switched projection region is on the back of the reference cross section
S (S04), and the projection image generator 63 projects the switched
projection region in a direction from the changed viewpoint Vp and
sequentially generates frame data of the S-side projection moving image
Dp (S05).

[0061]The explanation of the abovementioned ultrasound diagnosis apparatus
1 described above is given on the assumption that the entire scannable
range is scanned. Alternatively, the ultrasound diagnosis apparatus may
be configured to transmit and receive ultrasonic waves with part of the
scannable range as a scanning region, which can be switched, and change
the projection region and the viewpoint Vp in conjunction with the
switch. Below, an ultrasound diagnosis apparatus 1 in which part of the
scannable range is a scanning region and the scanning region is
switchable will be described.

[0062]The knob 122 is a switch for changing a scanning region. For
example, the knob 122 is switchable between positions to select the
region A or the region B adjacent to each other across the reference
cross section S. When the knob 122 is switched to the region A, the
controller 8 transmits delay data for scanning the region A to the
transmitter 3, displays the T-section frame 75 so as to cross the region
A, and outputs signals representing the switched projection region to the
image generator 6. When the knob 122 is switched to the region B, the
controller 8 transmits delay data for scanning the region B to the
transmitter 3, displays the T-section frame 75 so as to cross the region
B, and outputs signals representing the switched projection region to the
image generator 6. The trackball 121 is an operation part for changing
the viewpoint Vp. When the cursor 72 is put on the viewpoint object 76
and the trackball 121 is rotated while being pressed, the controller 8
changes the display position of the viewpoint object 76 with reference to
the axis Ax.

[0063]Moreover, based on the positional relationship between the changed
viewpoint Vp and the scannable range in the world coordinate system, the
controller 8 determines whether the region having a relationship in which
the reference cross section S is in front of the viewpoint Vp is the
region A or B, and transmits the delay data associated with the relevant
region to the transmitter 3. This determination is the same as the
process by the projection image generator 63, and a common program or a
common circuit may be used in configuration.

[0064]In the transmitter 3, the pulse generator 11 changes the scanning
region to a switched region by generating a delay in accordance with the
given delay data, or changes the scanning region to a region in which the
reference cross section S is in front of the viewpoint Vp in conjunction
with the change of the viewpoint Vp. The image generator 6 executes a
rendering process of projecting, in a direction from the viewpoint Vp,
the scanning region determined to have a relationship that the reference
cross section S is in front of the viewpoint Vp based on the positional
relationship between the switched scanning region or the changed
viewpoint Vp and the scannable range in the world coordinate system,
thereby generating the S-side projection moving image Dp.

[0065]Here, a combination of delay data representing the scanning region,
range information of the world coordinate system of the viewpoint Vp, and
the coordinate range in the world coordinate system of a region set as
the projection region may be previously associated with the switch of a
knob 122.

[0066]FIG. 8 is a flow chart illustrating the operation of changing the
scanning region and re-rendering in the ultrasound diagnosis apparatus 1
capable of switching part of the scannable range as the scanning region.

[0067]When the trackball 121 of the console 12 is operated and the display
position of the viewpoint object 76 is moved (S11, Yes), the controller 8
transmits delay data in which the region A or B existing on the back of
the reference cross section S when viewed from the viewpoint Vp is the
scanning region, to the transmitter 3, and causes it to transmit and
receive ultrasonic waves to and from this scanning region (S12). The
projection image generator 63 sequentially generates frame data of the
S-side projection moving image Dp with the region A or B existing on the
back of the reference cross section S when viewed from the viewpoint Vp
as the projection region (S13).

[0068]Further, when the knob 122 of the console 12 is operated and the
scanning region is switched (S14, Yes), the controller 8 transmits delay
data associated with the position of the knob 122 to the transmitter 3,
and causes it to transmit and receive ultrasonic waves to and from the
scanning region (S15). The coordinate transforming part 61 moves the
viewpoint Vp axisymmetrically about the axis Ax so that the switched
scanning region is on the back of the reference cross section S (S16),
and the projection image generator 63 projects the switched projection
region in a direction from the changed viewpoint Vp and sequentially
generates frame data of the S-side projection moving image Dp (S17).

[0070]Although the sections of the scanning region or projection region to
be changed are the region A and the region B in the above embodiment, it
is also possible to section into more regions in accordance with the
position of the knob 122. FIG. 9 is a schematic view taken from the
secondary scanning direction, illustrating an example of sectioning of
the scanning region or the projection region.

[0071]For example, as shown in FIG. 9, the scanning region or projection
region is sectioned into five regions C, D, E, F and G including
overlapping regions, and each of them is associated with a position of
the knob 122. For each of the regions C, D, E, F and G, a reference cross
section S is previously defined. The regions C, D, F and G are regions
that do not include the axis Ax, and the reference cross sections S
thereof are set on the boundary planes of the regions close to the axis
Ax. The region E is a region including the axis Ax, and the reference
cross section S thereof is a plane including the center of this region,
i.e., including the axis Ax.

[0072]Further, for each of the regions C, D, E, F and G, a viewpoint Vp is
previously defined so that the reference cross section S is in front and
each of the regions C, D, E, F and G is on the back. That is to say, the
controller 8 previously stores delay data for scanning the regions C, D,
E, F and G, and outputs the delay data of the region C, D, E, F or G to
the transmitter 3 in accordance with the position of the knob 122. The
sectional image generator 62 previously stores information representing
the position of the reference cross section S in association with the
position of the knob 122. Moreover, the projection image generator 63
previously stores positional information of the viewpoint Vp in
association with the position of the knob 122. For example, it is assumed
that the scanning region or projection region is switched sequentially
from the region E in the order of F, G, F, E, D, C, D, E in FIG. 9. In
this case, rendering is executed in the same direction from the viewpoint
Vp for the regions F, G, F, E. Then, when the region is switched to the
region D, the viewpoint Vp is moved axisymmetrically about the axis Ax
and directed reversely, and rendering is executed. Moreover, while the
region is changed from the region D in the order of C, D, E, rendering is
executed without change of the viewpoint Vp having been directed
reversely.

[0073]Thus, in the ultrasound diagnosis apparatus 1, in conjunction with
change of the projection region, the viewpoint Vp is changed to a
position that the reference cross section S is in front and the changed
projection region is on the back, and then the changed projection region
is rendered and an image is displayed. Furthermore, in the ultrasound
diagnosis apparatus 1, in conjunction with change of the viewpoint Vp,
the projection region is changed to the region A or B in which the
reference cross section S is in front and the changed viewpoint Vp is on
the back, a rendering process of projecting the projection region in a
direction from the changed viewpoint Vp is executed, and an image is
displayed on the monitor 7. Consequently, it is possible to maintain an
aspect of rendering at the viewpoint Vp with the viewpoint Vp having the
reference cross section S in front of the projection region without
executing a number of complicated operating procedures, e.g., the
operation of adjusting the projection region after the operation of
adjusting the viewpoint Vp and vice versa. Therefore, it becomes easier
to grasp a steric structure, thereby enhancing the efficiency of
observation of the inside of a subject.

[0074]Change of the viewpoint Vp in conjunction with the change of the
projection region may be change around the axis Ax in the depth direction
in the local coordinate system of the volume data. Alternatively, in the
operation of changing the viewpoint Vp, the change may be regulated to a
range around the axis Ax. Consequently, even if a projection region is
changed, the tilt of the projection region to be observed would not
change from above to below or from below to above.

[0075]Further, in the ultrasound diagnosis apparatus 1, in conjunction
with change of the scanning region, the viewpoint Vp is changed to a
position where the reference cross section S is in front and the
projection region is on the back, and then the changed projection region
is rendered and a image is displayed. Furthermore, in the ultrasound
diagnosis apparatus 1, in conjunction with change of the viewpoint Vp,
the scanning region is changed to the region A or B where the reference
cross section S is in front and the changed viewpoint Vp is on the back,
and then a rendering process of projecting the relevant scanning region
in the direction of the changed viewpoint Vp is executed and an image is
displayed on the monitor 7.

[0076]Consequently, it is possible to maintain an aspect of rendering at
the viewpoint Vp with the reference cross section S in front of the
projection region, without executing a number of complicated changing
operation steps, e.g., executing an operation of positioning the
viewpoint Vp and an operation of changing the projection region after an
operation of changing the scanning region, or executing an operation of
changing the scanning region and the projection region after an operation
of changing the viewpoint Vp. As a result, it becomes easier to grasp a
steric structure, and the efficiency of observation of the inside of a
subject increases.

[0077]Although the reference cross section S is previously set at a
predetermined position in the above embodiment, an arbitrary cross
section may be designated as the reference cross section S by an
operation through the console 12. The sectional image generator 62
generates the S-sectional moving image Ds by executing the MPR process on
the designated cross section. The projection image generator 63 places
the designated reference cross section S in front of the viewpoint Vp and
generates the S-side projection moving image Dp with the region existing
on the back as the projection region.

[0078]Further, although an example that the S-sectional moving image Ds
and the T-sectional moving image Dt are simultaneously displayed on the
screen is described in the above embodiment, only one of the above images
may be displayed. In the case of displaying only one of the above images,
the image generator 6 may generate only a sectional moving image to be
displayed. Moreover, although an example that these sectional moving
images and the S-side projection moving image Dp are simultaneously
displayed is described in the above embodiment, it is possible to
configure to first display only the sectional moving image and then
display the S-side projection moving image Dp. In other words, the term
"display" includes display of both the images at one time as well as
display of each of the images at different times.

[0079]Although the two-dimensional array type with the piezoelectric
elements 2a two-dimensionally arranged is described above as the
ultrasound probe 2 capable of three-dimensional scan, a mechanical 4D
type may be used.

[0080]The mechanical 4D type ultrasound probe 2 can perform
three-dimensional scan by one-dimensionally arranging the piezoelectric
elements 2a and mechanically oscillating the arrangement of the
piezoelectric elements 2a. Further, for the scan in the main scanning
direction, it is possible to employ not only electronic sector scan but
also electron linear scan or convex scan.